Patent GB-500039-A (GB)
Title: Improvements relating to aircraft locating devices
IPC: G01S1/72
Filed: 1937-06-30
Abstract: 500,039. Locating sounds and likevibrations; anti-aircraft-gun sights. SPERRY GYROSCOPE CO., Inc. June 30, 1937, Nos. 18171 and 18172. Convention dates, June 30, 1936 and May 21, 1937. [Class 118 (ii)] [Also in Group XXI] To compensate for target speed and /or for sound lag in a sound locator or a gun sight, an observing device is provided with a false target which is adjusted in accordance with target speed and a sight is trained on the false target, the movements of the sight being transmitted to set a searchlight or a gun. If the searchlight is situated at a point remote from the observing device, the instrument may be provided with an additional adjustment to compensate for parallax. As shown in Figs. 3, 4 and 6, the false target 90 is carried by a pantograph linkwork on the top of box 46, the box being turned in azimuth and elevation with the sound locator. The estimated target speed is set on the scale shown by rotation of knob 79 which displaces the pin 81 of the pantograph relative to the pin 73 of the box 46. The pin 73 carries a roller 75 which rides on the surface of sphere 54, the sphere being turned in two planes at rightangles by friction discs driven at rates proportional to the movement of the sound locator in azimuth and elevation, the drive from one roller being 2¢ times as fast as the drive from the other. The roller 75 moves over the surface of the sphere until the arm 75 lies in the resultant plane of rotation of the sphere and as the pin 81 is offset relative to the pin 73, the coupling between the two pins moves into this plane and the false target 90 is moved correspondingly. The sight 16 is maintained trained on the false target 90 and the line of sight 20, 19; 90 is parallel to the corrected direction of the target. The sound locator is set in the usual way by handles 13, 9 and the movements of the sight relative to the sound locator are controlled by handles 13', 9<1>. The movements of the sight relative to the ground are transmitted to the searchlight by transmitters 37, 38 which may be of the type described in Specification 415,201. The invention may be applied to a gun sight as shown in Fig. 11 in which the target is observed through telescope S instead of through a sound locator, the false target 90 being set and observed by sight 16 as described above. If the searchlight is situated away from the observing station an additional parallax correction must be made. For this the pantograph mechanism is provided with an additional link having an eccentric pivot 172, (see Fig. 19) set in accordance with the relative positions of observing and controlled stations. This is adjusted so that the line of observation of the false target is moved through an angle #<1>, from LB<1> to LA<1>, the path of the searchlight beam thus moving from SC to SB and reaching the target B. A full construction of this embodiment is given in the Specification. To enable binoculars to take over control from the sound locator when the target is sighted, the arrangement shown in Fig. 20 may be used. The sight 118 is maintained on the false target 122 with the left eye whilst the right eye looks for the target through one of the binoculars 140. When the target is sighted both eyes are transferred to binoculars 140 and movement of these controls the movements of the searchlight.